1. Field
Embodiments of the invention relate to the field of network processing; and more specifically, to centralized selection of a control network.
2. Background
A Network element (e.g., a router, switch, bridge, etc.) is a piece of networking equipment, including hardware and software, that communicatively interconnects other equipment on the network (e.g., other network elements, computer end stations, etc.). A network element includes a physical chassis (sometimes referred to as a shelf), which includes one or more networking cards (e.g., line cards, control cards, etc.). Control cards may implement one or more control networks (e.g., the control card may include a switch chip implementing a control network). The control network performs signaling, routing (including creation of and/or management of routing tables), bridging (including creation of and/or management of bridging tables) connection setup, session setup, etc. The line cards handle packet processing including forwarding and/or switching at a high speed (e.g., the line cards include application layer software).
Some network elements include redundant control networks such that upon failure of an active control network, a standby control network assumes the role as the active control network. Typically each line card is coupled with the active control network and the standby control network. For example, for each of the line cards, a first port is coupled with a port of the active control network and a second port is coupled with a port of the standby control network. If the active control network fails, the line card switches to the standby control network (which assumes the role as the active control network).
Some network elements use application layer software on each line card to manage the interfaces to the control networks. For example, for each line card coupled with the active and standby control networks, during normal operation, application layer software selects the port coupled with the active control network. Since application layer software is used to manage the interfaces to the control networks, these ports typically require separate network addresses and are visible to network software. Thus, rogue software and/or incorrectly configured software may use either interface to the control networks.
A bonding interface aggregates multiple links to present a single logical interface to application layer software. For example, a bonding interface may bond two physical links to two physical network elements. The bonding interface selects one of the two links to use. If a network element includes multiple bonding interfaces that each bond two different links to the same two network elements, each bonding interface independently selects which link (and thus which network element) to use. Bonding interfaces typically use Address Resolution Protocol (ARP), or other link state protocols (e.g., media independent interface signal), to determine whether the selected link is up or down. If the selected link is down, the bonding interfaces switches to the other interface.